Recently, an ink jet printer or plotter has been remarkably improved, and a high quality image of full color can be easily obtained. Thus, development of an ink jet recording material other than a conventional woodfree paper or coated paper for ink jet recording has been eagerly demanded.
Ink jet recording system comprises jetting very fine ink drops onto a recording material such as paper by various actions to form images, letters and the like on the recording material. An ink jet recording or plotter attracts a good deal of public attention since it has various characteristics that it is excellent in high-speed printability and low noisiness, that flexibility of a pattern to be recorded is large, that development-fixing step is not required, and further that a complex image can be precisely and rapidly formed. Particularly, it has been rapidly spread for various uses including a hard copy-producing device of image information of letters and various drawings prepared by a computer. Further, a multi-color recording can be easily carried out by using a plurality of ink nozzles. Multi-color ink jet system can provide a satisfactory color image comparable to those formed by multi-color printing system or color photographic system, and can provide copies at a lower cost as compared with printing technique or photographic technique when the copying number is small, and has been therefore widely applied.
Recently, an ink jet printer which provides a high quality image comparable to a silver salt photograph image is cheaply commercially available. An ink jet recording material is very low cost although it provides an image of the same quality as compared with silver salt photographic system, and this is a great economical merit for traders to frequently replace display images of a trade sample or an sign board which requires images of large area. Further, the ink jet recording system has an advantage that an image can be easily amended in respect to a color arrangement or layout by checking an image formed on a computer or its printed material, and it is quite impossible for conventional silver salt photographic system to enjoy this advantage.
An ink jet printer or plotter is lately noticeable to be used for preparation of a color artwork in printing field which requires a satisfactory image quality close to a photograph, or to be used for full color image recording such as output of a design image in design department or to be used for recording image information prepared by a computer on a transparent recording material which is then used for an OHP (overhead projector) in presentation of convention.
The above-mentioned demands for an ink jet printer or plotter or demands for a recording material are varied in proportion to a spread of an ink jet printer or plotter. For example, a recording material provided with an excellent outer appearance having a high glossy surface comparable to a silver salt color photograph or a highly transparent recording material usable as an OHP film, is demanded.
An effort has been made in respect to a device or an ink composition so that a usual printing or writing woodfree paper or coated paper can be used as a recording material for ink jet recording system. However, in proportion to an improvement in performances in respect to high speed, high precision or full coloring or in proportion to a spread of use of an ink jet recording device, higher performances are required also for a recording material. That is, the recording material is required to provide a light and clear color tone, to rapidly absorb an ink or to prevent bleeding of ink even when printed dots are overlapped. Particularly, in the case of color recording, not only single printing but also overprinting of yellow, magenta, cyan and black inks is conducted, and a very high performance is required since an ink deposition amount becomes large.
As a conventional ink Jet recording material, there has been proposed a recording material obtained by coating a silicon-containing pigment such as silica together with an aqueous binder on a paper surface, for example, as disclosed in JP-A-55-51583, JP-A-56-157, JP-A-57-107879, JP-A-57-107880, JP-A-59-230787, JP-A-62-160277, JP-A-62-184879, JP-A-62-183382 and JP-A-64-11877. An inorganic pigment such as silica has a large oil-absorbing capacity, and a recording material containing the inorganic pigment such as silica as the main component in an ink-absorbing layer is almost satisfactory in respect to an ink-absorbing capacity and an ink-absorbing speed, but there is a disadvantage that a recording material having a satisfactory surface gloss can not be obtained. When colloidal silica is used in place of silica for a purpose of obtaining a satisfactory gloss as disclosed in the above-mentioned JP-A-56-157, an ink-absorbing property becomes unsatisfactorily poor. JP-A-3-215082, JP-A-4-67986 and JP-A-5-32037 disclose a method for preparing a transparent recording material by coating a fine alumina sol together with a water-soluble binder on a support surface, but an ink-absorbing property is poor unless the ratio of the alumina sol (pseudoboehmite) to the binder in the coated layer is raised. However, the coated layer having a high pigment ratio easily generates cracking on the coated film when drying, and in order to obtain a satisfactory ink-absorbing capacity, the coated amount must be at least 20/m.sup.2, thus requiring a thick coating. Further, this provides such a problem that it is hard to control drying conditions in practical production. Still further, since a coating film strength is weak, an ink jet recorded image is easily peeled or damaged by being rubbed, and curl easily occurs after printing. Furthermore, since a transparency of the coated film is poor, a glossy surface can not be obtained even when a support having a high glossy surface is used. On the other hand, JP-A-6-320857 discloses an ink jet recording material having a glossy surface that is a cast-finished paper obtained by cast-finishing a coated paper while the coated layer is wet, but its surface gloss is very low as compared with a silver salt photograph and the quality of the silver salt photograph can not be obtained.
As mentioned above, in order to form an ink-absorbing layer having a high transparency or gloss, the above-mentioned various inorganic pigments are not employed or their amounts are limited when used, and therefore an ink-absorbing property is often provided by a resin layer formed on a support surface. Examples of the resins conventionally used for this purpose include polyvinyl pyrrolidone and vinyl pyrrolidone-vinyl acetate copolymer as disclosed in JP-A-57-38185 and JP-A-62-184879, a resin composition mainly containing polyvinyl alcohol as disclosed in JP-A-60-168651, JP-A-60-171143 and JP-A-61-134290, vinyl alcohol-olefin or styrene-maleic anhydride copolymer as disclosed in JP-A-60-234879, a crosslinked product of polyethylene oxide and isocyanate as disclosed in JP-A-61-74879, a mixture of carboxymethyl cellulose and polyethylene oxide as disclosed in JP-A-61-181679, a grafted polymer of polyvinyl alcohol with methacrylamide as disclosed in JP-A-61-132377, an acrylic polymer having a carboxyl group as disclosed in JP-A-62-220383, a polyvinyl acetal type polymer as disclosed in JP-A-4-214382 and various ink-absorbing polymers such as crosslinkable acrylic polymers as disclosed in JP-A-4-282282 and JP-A-4-285650. However, all of these ink-absorbing layer films are poor in water-resistance, and therefore, the ink-absorbing layer is dissolved by a solvent of ink when absorbing the ink. Consequently, when a printed part which is not fully dried is touched with any of other materials, the ink-absorbing layer film is broken and recording is damaged or the ink dye is attached to clothes. Further, the ink-absorbing layer film is dissolved with waterdrops and recording is damaged or the printed part provides an unpleasant feeling due to tackiness when touched with a hand. Still further, since contact between the ink-absorbing layer and other materials causes so-called blocking, the recorded images of the printed parts and the ink-absorbing layer films are sometimes broken.
An object of the present invention is to provide a recording material used for a printer or plotter employing ink jet recording system, and particularly to provide an ink jet recording material having a photographic paper-like gloss which is highly demanded for color recording or a highly transparent ink jet recording material usable as an OHP film.
Further, the present invention provides a recording film excellent in water-resistance, which prevents an ink-absorbing layer film from being dissolved with water drops or the like and also prevents a dye from bleeding from the film, a recording material which does not have such a tackiness on a printed part as to provide an unpleasant feeling when touched with a hand, and a recording material excellent in antiblocking property so that a recorded image on a printed part and an ink-absorbing layer film are not damaged by blocking.
The above-mentioned objects of the present invention can be accomplished by the following means, i.e. an ink jet recording material provided with an ink-absorbing layer on a support, wherein the ink-absorbing layer contains a gelatin crosslinked by at least one compound selected from the group consisting of compounds expressed by the following general formula 1, thereby providing a satisfactory photographic paper-like gloss a satisfactory transparency usable for an OHP, a high ink-absorbing speed and an excellent water-resistance. ##STR2##
In the above general formula 1, X is a bivalent residue having a carbonyl or sulfonyl group bonded with an N atom; each of R.sup.1 and R.sup.2 is a monovalent residue which may be the same or different, or R.sup.1 and R.sup.2 may bond each other to form a substituted or unsubstituted ring; R.sup.3 is a bivalent residue; and p is an integer of 0 or 1.
Particularly, among the compounds expressed by the general formula 1, compounds expressed by any of the following general formulas 2 to 4 are preferable. ##STR3##
In the above general formula 2, R.sup.1 to R.sup.3 are as defined in the above general formula 1. ##STR4##
In the above general formula 3, R.sup.1 to R.sup.3 and p are as defined in the above general formula 1. ##STR5##
In the above general formula 4, R.sup.1 to R.sup.3 and p are as defined in the above general formula 1.
The object of the present invention can also be accomplished by an ink jet recording material provided with an ink-absorbing layer on a support, wherein the ink-absorbing layer contains a gelatin crosslinked by at least one compound selected from the group consisting of compounds expressed by the following general formula 5. ##STR6##
In the above general formula 5, Ar.sup.+ is a substituted or unsubstituted 5-membered or 6-membered heterocyclic aromatic group having a quaternary nitrogen atom; n is an integer of 1 to 3; Y.sup.n- is a n-valent anion; and each of R.sup.4 and R.sup.5 is a monovalent residue which may be the same different or R.sup.4 and R.sup.5 may bond each other to form a substituted or unsubstituted ring.
Further, the object of the present invention can be accomplished by an ink jet recording material provided with an ink-absorbing layer on a support, wherein the ink-absorbing layer contains a gelatin crosslinked by at least one compound selected from the group consisting of compounds expressed by the following general formula 6. ##STR7##
In the above general formula 6, R.sup.6 is a bivalent residue and q is an integer of 0 or 1.
Still further, in the ink jet recording material provided with an ink-absorbing layer on a support, an ink-absorbing property can be more improved by providing an ink-absorbing layer containing at least one hydrophilic polymer in addition to a gelatin crosslinked with the above-mentioned crosslinking agent. A hydrophilic polymer containing at least one monomer selected from the group consisting of acrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N-isopropylacrylamide, acryloylmorpholine and N-vinyl-2-pyrrolidone as a constitution unit or a water-soluble cellulose ether is preferable in view of ink-absorbing property.
Further, in order to enhance a fixing property of a dye, it is preferable that these hydrophilic polymers contain at least one ammonium salt monomer as a constitution unit.
On the other hand, an ink jet recording material having a satisfactory photographic paper-like gloss, a satisfactory transparency usable for an OHP, a high ink-absorbing speed and an excellent water-resistance can be provided by incorporating a gelatin grafted with a hydrophilic monomer into an ink-absorbing layer provided on a support.
By incorporating a gelatin grafted with a hydrophilic monomer into an ink-absorbing layer, the tackiness of a printed part can be made lower.
In view of an ink-absorbing property, a gelatin grafted with a hydrophilic monomer contains preferably at least one hydrophilic monomer selected from the group consisting of acrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N-isopropylacrylamide, acryloylmorpholine and N-vinyl-2-pyrrolidone as a constitution unit.
Further, in order to enhance a fixing property of a dye, it is preferable that a grafted gelatin contains at least one ammonium salt monomer as a constitution unit.
Still further, in order to enhance a water-resistance, it is preferable that a grafted gelatin is crosslinked with a crosslinking agent. It is particularly preferable in view of an ink-absorbing property and a film strength that the crosslinking agent is at least one member selected from the group consisting of compounds expressed by any of the above general formulas 1 to 6.
On the other hand, by incorporating an organic polymer fine particle comprising a resin having a refractive index of at most 1.7 into an ink-absorbing layer, an ink jet recording material effectively preventing a recorded image from being damaged by blocking without substantially losing a gloss and a transparency can be provided.
Further, by incorporating an inorganic pigment fine particle having a refractive index of at most 1.7 into an ink-absorbing layer, an ink jet recording material preventing a recorded image from being damaged by contacting with other materials without substantially losing a gloss and a transparency can be provided. An amorphous silica having an average agglomerate particle size in the range of from 2 .mu.m to 20 .mu.m is preferable as the inorganic pigment fine particle since it does not impair a gloss and a transparency.
On the other hand, by providing an ink-absorbing layer formed by coating a coating solution on a support and drying the coated solution without gelling, a recording material having a more satisfactory ink-absorbing property can be provided.
A technique for crosslinking gelatin with a crosslinking agent is already practically used in various fields mainly including a photographic industry. Further, heretofore, many compounds are known to be effective as a crosslinking agent for gelatin.
Examples of the crosslinking agent include aldehyde type compounds such as formaldehyde, glutaraldehyde or succinaldehyde, those disclosed in U.S. Pat. No. 3,288,775 and No. 2,732,303 and British Patents No. 974,723 and No. 1,167,207, compounds having a reactive halogen such as 2-hydroxy-4,6-dichloro-triazine salt, ketone compounds such as diacetylcyclopentanedione, divinylsulfone, 5-acetyl-1,3-diacryloyl, compounds having a reactive olefin as disclosed in U.S. Pat. No. 3,635,718 and No. 2,232,763 and British Patent No. 994,869, N-hydroxymethylphthalimide, N-methylol compounds as disclosed in U.S. Pat. No. 2,732,316 and No. 2,586,168, isocyanates as disclosed in U.S. Pat. No. 3,103,437, aziridine compounds as disclosed in U.S. Pat. No. 3,017,280 and No. 2,983,611, acid derivatives as disclosed in U.S. Pat. No. 2,725,294 and No. 2,725,295, carbodiimide type compounds as disclosed in U.S. Pat. No. 3,100,704, epoxy compounds as disclosed in U.S. Pat. No. 3,091,537, isoxazole type compounds as disclosed in U.S. Pat. No. 3,321,313 and No. 3,543,292, halogenocarboxyaldehydes such as mucochloric acid, dioxane derivatives such as dihydroxydioxane and dichlorodioxane, blocked isocyanates as disclosed in JP-A-53-113856, active acyl compounds, inorganic crosslinking agents such as chromium alum and chromium trichloride, and the like.
Substantially all of these crosslinking agents were developed in the field of a photographic industry, and were developed for the purposes of improving a mechanical strength of a film and controlling water-absorption. Therefore, it is usual that an ink containing a large amount of water for ink jet recording is hardly absorbed when gelatin is crosslinked by these crosslinking agents.
A property required for ink jet recording is to impart a water-resistance to an ink-absorbing layer without impairing an ink-absorptivity of the ink-absorbing layer to absorb an ink containing a large amount of water for ink jet recording.
An advantage of using gelatin is that tackiness of the surface of an ink-absorbing layer containing gelatin is small regardless of an unprinted part or a printed part. When an ink-absorbing layer is constituted by other natural polymer or synthetic polymer, a water content is liable not to evaporate by drying and a high boiling point solvent such as glycerin in the ink component remains on the surface of the ink-absorbing layer, thus providing a large tackiness on a printed part absorbing ink on the ink-absorbing layer surface. However, since gelatin contains a hydrophobic group and a hydrophilic group in good balance, it absorbs and holds a non-volatile solvent such as glycerin. Also, gelatin provides a very strong film strength and is swollen with an ink component but is not eluted, and therefore tackiness of a printed part on the surface of an ink-absorbing layer is small.
Further, an ink-absorbing layer containing gelatin causes a volume change of at least twice as large as a dry film thickness when absorbing a water content, and accordingly it has a large ink-absorbing capacity.
As a result of earnest study, the present inventors could provide a satisfactory ink jet recording material by crosslinking gelatin with a specific crosslinking agent, which imparts a water-resistance to an ink-absorbing layer without impairing an ink-absorptivity and protects a recorded image from being damaged by breakage of a film of the ink-absorbing layer with water drops or the like.